Stitch changing device in a zigzag sewing machine



April 21, 1970 AKIO KOMURO 3,507,236

STITCH CHANGING DEVICE IN A ZIGZAG SEWING MACHINE Filed Feb. 15,1967 4 Sheets-Sheet 1 INVENTOR. /)/(/0 KOM URO n'r-roPNEYs April 21, 1970 AKIO KOMURO ,507,

STITCH CHANGING DEVICE IN A ZI GZAG SEWING MACHINE Filed Feb 15, 196

4 Sheets-Sheet 2 m T N E V m AK/O KU/VHJRO RTTORNEYS April 1, 1970 AKIO KOMURO 3,507,236

STITCH CHANGING DEVICE IN A ZIGZAG SEWING MACHINE Filed Feb. 15, 196"! I 4 Sheets-Sheet 5 INVENTOR. H Kl 0 K0 M U R 0 ATTORNEYS A ril 21, 1970 AKIO KOMURO 3,507,236

STITCH CHANGING DEVICE IN A ZIGZAG SEWING MACHINE Filed Feb. 15, 1967 4 Sheets-Sheet F1515 FIE-.6 IE 7 INVENTOR.

AKro KOMURO M WQ ZZT ATTORNE United States Patent US. Cl. 112-158 2 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a zigzag sewing machine and more particularly to a stitch changing device for the zigzag sewing machine which serves to change or skip the usual stitches to make a long pitch of straight line stitches, especially for basting operation.

Standard zigzag sewing machines are constructed for making comparatively fine feeding pitches to zigzag stitches while making use of the lateral oscillations of the needle bar and shuttle as well as the movement of the feeding mechanism. However, in an actual sewing operation it often becomes necessary for the operator to sew the fabric for basting or for preventing fray at the outer edge of the fabric. If such a temporary stitching is to be made by the aforementioned zigzag sewing machine, a large quantity of thread is required, and moreover, the stitches will be stiff for only such a temporary and cause trouble in loosening the same afterwards. Consequently, such fray stopping stitches or basting stitches are to be made by a quite different stitching means. The present invention is intended to neat-1y eliminate the aforementioned defects of the conventional zigzag sewing machine.

The fundamental object of the present invention is to enable the standard zigzag sewing machine to make such basting or fray-stop stitching besides the usual zigzag stitching and other various pattern stitching, by changing the moving phase of the needle with respect to the shuttle turning below the needle, thereby to prevent the shuttle from catching the thread loop made by the needle on either side of the lateral dropping positions of the needle, and then to achieve the aforementioned purpose for basting or fray-stop stitching. Thus the general sewing operations including such basting or fray-stop stitching may be carried out by use of a single zigzag sewing machine. Especially such basting or fraystop stitching operation can be far more easily and effectively conducted, and the conventionally conducted uneffective manual operation becomes unnecessary.

Another object of the present invention is to provide the standard zigzag sewing machine with a simple adjusting means for changing the aforementioned moving phase of the needle with respect to the shuttle below the needle. For this purpose, according to the present invention, a circular operating parts is arranged on the needle bar or other component members in connection with the needle bar so as to enable the operator to operate said circular operating part. Thereby the aforementioned purpose of the present invention can be carried out and the means therefor are simple and positive in operation and can be easily adapted to the standard zigzag sewing machine.

The many novel features and working of the present invention will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a front elevational view of a sewing ma- 3,507,236 Patented Apr. 21, 1970 chine with cover plate and parts removed to show the sewing mechanism in accordance with the present invention.

FIG. 2 is a side elevational view of the front part of the sewing machine illustrated in FIG. 1.

FIG. 3 is a front elevational view of the shuttle mechanism illustrating the crossing condition of the needle and the shuttle hook.

FIG. 3-1 is a diagram of the relative operational positions of the elements of FIG. 3.

FIG. 4 is similar to FIG. 3 but with the needles raised.

FIG. 4-1 is a diagram of the relative operational positions of the elements of FIG. 4.

FIG. 5 is a plan view of the typical stitches formed by the standard zigzag cam stitch.

FIG. 6 is a plan view of the provided by using a blind stitch formation provided by using a blind stitch cam.

FIG. 7 is an illustration of a straight stitch formation provided by the use of the standard zigzag stitch cam in connection with the present adjusting device.

FIG. 8 is an illustration of a ling pitch of a straight stitch formation provided by using a blind stitch cam in connection with the present adjusting device.

FIG. 9 is a front elevational view partly in section of an embodiment of the adjusting device of the present invention.

FIG. 10 is an illustration of two needles which are another embodiment of the adjusting device according to the present invention.

FIG. 11 is a side view, partly in section, of the lower part of the needle bar illustrating a further embodiment of the adjusting device according to the present invention.

FIG. 12 is a side view of a portion of the needle bar and adjustable crank therefor which is another embodiment of the adjusting device of the present invention.

Referring to the drawings, the sewing machine mechanism illustrated in FIG. 1 and FIG. 2 is that of a conventional standard zigzag sewing machine with feed mechanism connected to the main drive shaft, the needle bar mechanism which reciprocates up and down while oscillating laterally in the right and left directions, and shuttle mechanism which also oscillates in accordance with the needle bar mechanism catch the thread loop formed by the needle so as to form stitches with the under thread drawn from the bobbin. In an embodiment of the present invention, however, in a zigzag sewing machine as described above, the crossing condition of the needle and the shuttle is changed by elevating the bottom position in the vertical reciprocating movement of the needle bar 7 to a suitable degree with respect to the loop catching hook 30 of the shuttle to change the crossing positions of the hook and the needle. In other words, by intentionally preventing the hook from catching the thread loop on either side of the lateral dropping position of the needle while continuing to catch the thread loop thereof. In this kind of zigzag sewing machine, the needle moves downwardly to the lateral dropping position 20 or 20" alternately as illustrated in FIG. 2. It is apparent that the crossing condition of the hook 30 of shuttle 24 and the needle 20, in which the thread loop is caught by the hook 30, is better when the needle drops to the left side position 20" in this case than when the needle drops to the right side position 20 due to the difference of phase between the reciprocating movement of the needle and the turning movement of the shuttle; therefore, the needle dropping to the right side position 20' must be made to take a movement phase with respect to the turning shuttle in which the thread loop made by the needle may be positively caught by the hook of the shuttle. With such setting the zigzag sewing machine is made to form the usual zigzag stitches.

On the other hand if such a phase relation between the needle and the shuttle is changed by shifting the lowest dead point of the needle bar a little in the upward direction, the relation is established between the needle and the shuttle in which when the needle drops to the right side position 20 the thread loop made there by the needle is never caught by the hook 30 of shuttle 24 while the thread loop made by the needle dropping to the left side position 20" continues to be caught by the hook 30 of shuttle 24. In such a manner a comparatively long pitch of straight stitches are formed on one side of the lateral dropping positions of the needle as if so much feeding was applied to the stitched cloth. Such long seams are very suitable for basting or such a kind of sewing operation. Especially if a blind stitch cam or a standard zigzag cam is employed in connection with the adjusting device of the present invention the aforementioned purpose of the present invention will be effectively achieved.

The compositions, features, advantages and the effects of the functions of the present invention will be clearly understood from the following concrete description of the preferred embodiment of the present invention. The balance crank 6, as best shown in FIG. 12, fixedly mounted on the front end of the drive shaft 2 which, being rotatably supported through the machine arm 1, is rotated by the well-known driving mechanism (not shown); a crank 5 which is provided at the opposite ends on the opposite sides thereof with the studs 5a and 5b is fixed by studs, the stud 5b to the eccentrical position of the balance crank 6, and on this stud 512 between the crank 5 and balance crank 6 is turnably mounted a balance 4 at its one end, and to the other stud 5a is turnably connected a needle bar crank rod 3. The middle portion of the balance 4 is pivotally supported at 40 by one end of the restricting rod 39 whose other end is pivotally connected at 38 to the machine arm 1, thus making the well-known quick return movement. As is well known, in order to effectively draw up the thread through thread hole 41 in balance 4 and tighten the same. The stud 10 is connected to the needle bar holder 8 by the pin 9, turnably connected to the lower end of the needle bar crank rod 3. Furthermore the needle bar holder 8 holds the needle bar 7 vertically. To the support base 35 at the end of the machine arm 1, the needle bar support 12 is oscillatably supported by the stud 13, a resilient washer 14 is positioned between needle bar support 12 and stud 13 to prevent the needle support 12 from moving from the supporting base 35'.

The needle bar support 12 is usually urged in one direction by the spring 16 whose top is fixed to the machine arm by the screw 15. On the other hand, the lower part of the needle bar support 12, is pivotally connected by screw 18 to one end of the rocking connector 117 and its other end is connected to the zigzag generator (not illustrated) fitted in the machine arm 1. At the lower end of the needle bar 7, there is provided a needle fitting groove 19 into which needle 20 is inserted and the needle cramp 21 is provided to fix the needle 20 inserted in the groove 19 by means of its setscrew 37.

Referring to FIG. 9 screw-threaded portion 32 and a fine vertical groove 34 are formed at appropriate longitudinal portion on the outside of the needle bar 7. 0n the screw-threaded portion 32, the rotary ring 11 is in threaded engagement therewith and also is located in the recess 33 of the needle bar holder 8 concentrically with the needle bar 7. Further, the needle bar holder is formed at its lower end with projection 47 slidably fitted into the aforesaid fine groove 34 to prevent the needle bar holder from turning on needle bar 7 and also to guide the longitudinal movement of the needle bar in the needle bar holder. With this arrangement, if ring 11 is rotated in one direction the needle bar 7 is moved in the upper direction and, thus, the lowest dead point of the needle bar is shifted in the same direction.

In connection with the described construction, the

shuttle mechanism as used in a standard sewing machine is provided under the machine bed 22. This shuttle mechanism is constructed so that the shuttle hook 24 is rotatably located in the shuttle race 23 and held therein by a cap 25 and cap retainers 26. The shuttle hook 24 is provided, with the bobbin case 28 in which the bobbin (not illustrated) is mounted and an oscillating turning movement is given to the shuttle hook by the drive element 29 fixed to one end of a conventional lower shaft (not illustrated) which is driving from the upper drive shaft 2. In this sewing machine, since the shuttle 24 catches the thread loop when it turns in the clockwise direction during its oscillating movement, the needle bar 7 is set so as to bring about the loop catching phase relation between the needle 20 and the shuttle 24 at the position 20 which is one of the lateral positions to which the laterally oscillating needle drops. If the sewing machine is so constructed as to make the shuttle catch the thread loop when it turns in the counterclockwise direction, the needle bar has to be set so as to bring about the loop catching phase relation between the needle and the shuttle at the position, for example position 20".

In this condition if the sewing machine is driven with the upper and lower threads applied, the upper thread loop is caught by the book 30 of shuttle 24 and interlocked with the lower thread to form seams. If the sewing machine is driven with the standard zigzag cam or blind stitch cam employed the stitches as illustrated at FIG. 5 or FIG. 6 are formed as generally known.

According to the present invention, when the aforementioned ring 11 is turned in one direction to shift the needle bar 7 a little in the upward direction the hook 30 of shuttle 24 continuously fails to catch the thread loop on one side position 20 of the lateral needle drop positions 20' 20". Namely, in the ordinary domestic zigzag sewing machine the needle bar 7 is appropriately set so as to bring about the loop catching phase relation between the needle and the shuttle as illustrated at FIG. 3 in which the hook 30 of the shuttle 24 crosses the upgoing needle 20 on the lateral needle drop positions 20' 20 in a very good crossing condition and never fails to catch the thread loop formed by the upgoing needle 20 on both needle drop positions 20' 20 The diagramatical illustration at FIG. 31 more clearly shows the crossing condition of the needle 20 and the hook 30 of shuttle 24. Whereas, if the ring 11 of the present invention is turned to raise the needle bar 7 in order to shift the lowest dead point of the needle bar and accordingly, that of the needle 7 a little in the upward direction as illustrated at FIG. 4 the crossing condition is immediately worsened between the hook 30 of shuttle 24 and the upgoing needle 20 at one side position 20' of the lateral needle dropping positions 20' 20", and the hook 30 continuously fails to catch the thread loop formed by the upgoing needle at that position 20' while it continues to catch the thread loop formed by the upgoing needle at the opposite needle dropping position 20". The diagrarnatical illustration at FIG. 4-1 more clearly shows the changed crossing con dition of the hook 3G and the needle 20 in which the book 30 crosses the needle 20 on the right side at the level of the needle eye and never to catch the thread loop formed by the needle while the hook 30 in the diagrarnatical illustration at FIG. 3-1 crosses the needle 20 on the right side in a course above the level of the needle eye.

If the sewing machine is driven with the standard zigzag stitching cam employed in connection with the device of this invention, the resultant seams are just like the ones illustrated at FIG. 7; and if the blind stitching cam is employed the resultant seams are just like the ones illustrated at FIG. 8. All of these seams are formed on the left side needle dropping position 20" where the upper thread 36 and the lower thread are positively interlocked in the shuttle 24. The seams illustrated at FIG. 7 are of straight with the feeding pitch twice as long as that of the standard zigzag seams illustrated at FIG. 5 and are suitable for preventing the fray at the cut edge of the cloth when applied especially to a kind of toweling. On the other hand, the seams illustrated at FIG. 8 are of straight with the feeding pitch several times as long as that of the seams on the right side of the blind stitch illustrated at FIG. 6 and are suitable for basting any kind of cloths.

Another embodiment of the stitch changing means according to the present invention is shown in FIG. 10. As an object of the present invention is to adjust and change the phasic relation between the hook 30 of the shuttle mechanism under operating condition and the eye of the needle 26 as shown in FIG. 3 and FIG. 4 or FIG. 31 and FIG. 4l, for attaining such technical purpose, the same relation can be obtained by using the needle a which is shorter than the usual needle 20 for standard sewing by a length equivalent to the distance A as illustrated at FIG. 41, instead of the aforesaid rotary ring 11. Such change over from the needle 20 to the needle 20a can be accomplished comparatively easily by operation of the setscrew 37 against the needle stopper 21.

Another embodiment according to the present invention is illustrated in FIG. 11. In this embodiment, the needle bar 7 is divided into the upper portion 7a suspended from the machine arm and the lower needle attaching portion 71), a screw-threaded cylinder 42 with female screw-threads 44 is attached to upper portion 7a, and the male screw-thread 43 formed at the top of the lower portion 7b is in threaded engagement with the female screw-thread 44, thereby feeding the lower needle bar portion 711 into the screw-threaded cylinder 42. The needle 20 is provided at the bottom of lower portion 7b and is lifted to raise the position of the eye of the needle. Thus in the same way as in the aforesaid case the phasic relation between the needles eye and the hook of the shuttle mechanism can be changed. The needle bar 7 is provided at the part thereof below the needle bar holder 8 with ring 42, where the adjustment can be made, thereby the working mechanism for driving the needle bar 7 added to this needle bar holding portion is quite free from influence.

Further another embodiment according to the present invention is shown in FIG. 12. In this case illustrated in FIG. 12, the needle bar crank 8 is fixed to the needle bar 7 by the setscrew 31 as is well known, in which condition the turnbuckle 45 is in threaded engagement with the threaded ends of a two piece needle bar crank rod 3. By extending or shortening the needle bar crank rod 3 by rotating this turnbuckle 45, the needle bar 7 fixed to the end of its needle bar crank rod 3 with the setscrew 31 is moved up or down. As the needle bar 7 is slidably supported by the needle bar support 12, the phasic relation between the needle at the bottom of the needle bar 7 and the hook 30 of the shuttle mechanism in case of operation can be changed by the extending or shortening operation of the needle bar crank rod 3 quite in the same way as in case of the embodiments described hereinbefore. With this structure it will be easily understood that by turning the turnbuckle 45 the needle bar crank 3 is longitudinally lengthened or shortened. Therefore, if the turnbuckle 45 is turned in one direction and the needle bar crank 30 is shortened, the needle bar 7, which is longitudinally slidably supported in the needle bar support 12, is accordingly, raised by means of the needle bar cramp 8 which is fixed on the needle bar by set screw 31 and connected to the lower end of the needle bar crank 3 by the stud 10 and the pin 9. Thus, the lowest dead point of the needle bar 7 and accordingly, that of the needle 20 is shifted in the upward direction relative to the shuttle, and all in the same effect the crossing relation between the needle 20 and the hook 30 of shuttle 24 is brought about just as illustrated at FIG. 41 in which as stated hereinbefore, the hook 30 continuously fails to catch the thread loop formed by the needle on the right side while it continues to positively catch the thread loop formed by the needle on the left side, thereby to form the seams as illustrated at FIGS. 7 and 8 on the left side line of the zigzag stitches, especially when the standard zigzag stitching cam and the blind stitching cam are respectively employed in connection with the device of the present invention.

-Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a zigzag sewing machine having in combination a frame, a drive shaft longitudinally mounted in said frame, a needle bar support oscillatably supported on said frame and spring biased in one direction, a needle bar slidably supported by said needle bar support, crank means including a needle bar crank rod and a needle bar holder located between said drive shaft and said needle bar, oscillation generating means, an oscillation transmitting rod connected at one end to said needle bar support and at the other end connected to said oscillation generating means, a needle attached to the lower end of said needle bar and furnished with a thread, and shuttle means provided below the machine bed and including a shuttle having a bobbin case therein with a hook oscillating to catch a thread loop formed by said needle and to interlock the same with an under thread furnished in said bobbin case to produce zigzag stitches, a stitch changing device being capable of shifting the lowest dead point of said needle bar in the upward direction, whereby the crossing relation between said needle and said shuttle can be changed so that said hook of said shuttle fails to catch the thread loop formed by said needle dropping to one side of the lateral needle drop positions of said zigzag stitch, thereby to produce straight stitches, said stitch changing device including a recess formed in said needle bar holder, and a threaded ring located in said recess, which ring is concentric with said needle bar and is in threaded engagement with said needle bar, and being adapted to be turned thereby to longitudinally shift said needle bar with respect to said needle bar cramp.

2. In a zigzag sewing machine as set forth in claim 1, wherein a groove is formed longitudinally on said needle bar, and a lug is formed on said needle bar holder and engaged in said groove for preventing the relative turning movement of said needle bar and said needle bar holder, and for guiding the longitudinal movement of said needle bar.

References Cited UNITED STATES PATENTS 933,235 9/1909 Craige 112-221 3,362,363 1/1968 Bono 112-158 FOREIGN PATENTS 1,433,041 2/ 1966 France.

H. HAMPTON HUNTER, Primary Examiner US. Cl. X.R. l12221 

